Method of producing cast iron



Patented Feb. 23, 1926.

UNITED STATES I 1,513,937 PATENT OFFICE.

JOHN CLIFTON HENDERSON, OF NEW YORK, N. Y., ASSIGNOR TO DRIVER-HARRIS COMPANY, OF HARRISON, NEW JERSEY, A CORPORATION OF NEW JERSEY.

METHOD OF PRODUCING CAST IRON.

No Drawing.

To all whom it may concern:

Be' it known that I, JOHN C. HENDERSON, a citizen of the United States, residing at New York, county of New York, State of New York, have invented a certain new and useful Iniprovement in Methods of Producing Cast Iron, of which the following is a full, clear, and exact description.

My invention relates to a new and improved method of producing cast iron containing nickel and chromium in relatively small but definite quantities. It is known that small additions of nickel and chromium to cast iron produced an improved product having better I wear-resisting properties, greater tensile strength and greater density.

RIn. proper proportions it is particularly suited forcylinder blocks for internal combustion engines used in automobiles and the like and for high temperature engine valves and high. pressure steam and water valves, bottle molds and electric resistance grids. These are prominent among the present fields known to me in which such cast iron is adapted to be used. "Heretofore there has been serious difiiculty in introducing the nickel and chromium into the iron and securing the proper proportions in the product. This has been due in part to the high melting temperature of nickel, of ferro-nickel, of chromium andof term-chromium, and also to the fact that the chromium content is readily oxidizable and is apt to slag ofi. The object of my invention is to produce a method in which these difliculties are reduced and in which the proportions of the constituents of the final product can be more accurately determined and controlled.

In carryingout my method. I form an alloy consisting essentially of nickel, chromium and iron, in which the nickel is five times as great as the chromium and in which the iron is present in a considerable quantity so as to produce an alloy having a lower melting temperature than nickel or chromium, or lowcarbon ferro-nickel or ferrochromium. I preferably. make this alloy high in carbon so as to still further reduce its melting temperature- Thus the preferred alloy is approximately nickel five parts, chromium one part, iron about two parts and carbon .60% to 1.50%, a good percentage being nickel chromium 12%, iron- 27%, carbon 1%. This alloy has a :melting temperature of about 2200 F. and

Application filed April 22, 1925. Serial No. 25,119.

is, before introduction into the iron, shot-ted or made up into notched bars from which sections can be easily broken. I then introduce it into the molten iron in the ladle in proper quantity. The high carbon alloy I use readily mixes with the molten iron and does not form hard spots such as are liable to occur when high carbon ferrochromium is used. Low carbon ferrochromium is hard to melt and 'rurthermore is so high in cost as to be objectionable for that reason also.

In my method I first heat the iron in a cupola or other suitable furnace to a temperature well above the melting temperature of the alloy, say 2500 to 2700 F. I then pour some of the molten iron into a ladle until the bottom of the ladle is well covered. I then place in the proper amount of the alloy and fill the ladle from the cupola until the desired quantity of iron is obtained. The highly heated molten iron melts the alloy and the resultant stirring motion causes its constituents to mingle with the iron without reducing the temperature of the combined mixture below the proper pouring temperature. I then pour the mixture into molds in the ordinary manner.

In the final product I preferably have Percent. Nickel .45 t0 2.40, Chromium .09 to i .48 Carbon 3.25 to 4.25 Iron 95.37 to 91.95

the balance being composed of the other ordinary constituents of cast iron.

Inasmuch as the alloy has about five times as much nickel as chromium it is only necessary to add the amount of iron, with the usual carbon content for cast iron (3% to 4%), necessary to dilute the alloy to the desired extent in accordance with well known furnace practice. Thus one pound and a half, or two pounds, of alloy with one hundred ounds of molten iron having the usual car on content for cast iron would produce good results, or, in other words, the preferred result can be obtained by introducing into a ladle highly heated molten iron and an amount of the alloy in solid form equal to 1.5% or 2% of the molten iron. The amount of alloy can for some purposes be varied from 0.75% to 4%.

The introduction of the nickel and chromium into the ladle in the form of a nickel into the cupola in the form of an alloy or as separate constituents is an important feature of my invention since a substantial loss in tainin the chromium content due to oxidation or slagging ofi is avoided so that the composition of the product is more definite, the cost of operation is reduced and the product on account of the stirring action has the alloying elements more uniformly distributed.

As will be evident to those skilled in the art, my invention permits of various modifications without departing from the spirit thereof or the scope of the appended claims.

What I claim is:

1. The method of producing cast iron containing definite quantities of nickel and chromium which consists in forming an alloy of nickel, chromium and iron, high in carbon so as to have a relatively low melting point, the nickel beingin excess of the chromium and iron taken together, introducing said alloy, in solid form, and molten iron into a ladle, and producing thereby a molten alloyed mass having the desired pouring temperature.

2. The method of producing cast iron condefinite quantities of 'nickel and chromium, which consists in forming an alloy of nickel, chromium and iron, high in carbon so as to have a relatively low melting point, the iron being in excess of the chromium and the nickel being in excess of the chromium and iron taken together,

carbon so as to have a relatively low melt- 1 ing point, the nickel in the alloy being approximately five times as much as the chromium, and the carbon in the alloy being from six-tenths per cent (.60%) to fifteentenths per cent (1.50%) introducing said at loy, in solid form, and molten iron into a ladle, and producing thereby a molten alloyed mass having the desired pouring temperature.

4. The method of incorporating nickel and chromium into cast iron, which consists in forming an alloy of nickel, chromium and carbon, the melting point of which is less than the melting point of molten cast iron, introducing said alloy in solid form and molten iron into a ladle and producing thereby a molten'alloyed mass having the desired pouring temperature,

In testimony whereof, I have signed my name to this specification this 20th day of April, 1925.

JOHN CLTFTUN HENDERSQN. 

